Rogue is pretty powerful right now. It might get nerfed by the time you hit 70, but right now it and warrior are the hunny bunnies of WoW. A rogue with aoe silence is pwn.
Mages can aoe grind, nuke, never buy food/water and get a dungeon group easy.
Hunter is easy and that may be why I never got one past lvl 40. It is so easy it kind of gets boring. Plus, you're fighting the huntard stygma.
WILD CARD CHOICE: Shaman! The close bro to druid, the hybrid without a tanking form, but one of the fastest leveling classes in game. Level enhancement, blow through enemies, dominate PvP pre-BC and have fun. You get ghostwolf at 20 to make quest running easier and a self rez later on. At 70 you can be resto and have one of the best heals in the game, stay enhancement to be a melee buff or try Ele and blow things up so crazy fast you'll laugh. I two-shot most of the IQD mobs as I daily quest, critting at about a 40% clip on my nature spells. Since Lightning Bolt and Chainlightning casted back to back hit at the same time, plus lightning overload, I sometime double-double crit for 9k at once. Of course you have no aggro drop and when things proc I kind of bite my teeth hoping that I didn't pull aggro off the raid boss.
Oh and also Heroism/Bloodlust is ace.
On the downside you get ignored every patch and the class has serious CC issues and some basic things that every class has that it completely lacks. (A melee spec with no cc removal? a casting spec with no spell pushback resist?)
Overall, rogue is the hottest class right now. All the old counters to the class have been removed over time. Hel,l Rogues even kill Warriors these days.